Conventional silicon etchants are classified as acidic or basic. Acidic etchants include solutions of nitric acid and hydrofluoric acid. Acidic silicon etchants employ a strong oxidizing agent which produce etching rates to fast for good control. Acidic silicon etchants are generally nonselective between silicon and phosphosilicate glass (PSG), and frequently etch PSG at a much faster rate than silicon. The strong oxidant present results in the uncontrolled formation of silicon dioxide layer on the silicon which results in extended exposure of uncovered surfaces to the etchant thereby resulting in a pitted surface. On the other hand, conventional basic silicon etchants generally contain a basic oxidant and a complexing agent which attacks organic photoresists, therefore requiring the necessity of an oxide mask. One of the disadvantages of an oxide mask is that it leaves a "shelf" at the edges of the etched region which can result in shorting and occlusion problems.